A dichlorodifluoroethylene (systematically named dichlorodifluoroethene) is one of three compounds with the chemical formulaC2Cl2F2. Dichlorodifluoroethylenes are colourless gases, and are some of the simplest chlorodifluoroalkenes.

Contents

1,1-Dichloro-2,2-difluoroethylene is a low-boiling liquid that is used a refrigerant.[3] It may also be used as a solvent, but has practical limitations as such, because of its low boiling point (commercial listings, 19 °C; lit. 17 °C).[4]

It is regarded as a hazardous chemical for being toxic by inhalation (see MSDS), and a low-boiling liquid, and it causes irritation when it comes into contact with the skin and mucous membranes. Its ASHRAE number is R-1112a, and its CAS number is 79-35-6. Concentrated 1,1-dichloro-2,2-difluoroethylene can be ignited with ease in the laboratory.

The diastereomers were co-isolated first in 1965, by using a combination of fractional melting and fractional distillation.[5] The cis isomer's ASHRAE number is R-1112c, and its CAS number is 311-81-9. Its melting point is −119.6 °C (−183.3 °F).[5] The trans isomer's ASHRAE number is R-1112t, and its CAS number is 381-71-5. Its melting point is −93.3 °C (−135.9 °F).[5] The diastereomers are commercially only available as a mixtures of varying proportions.

1.
ChemSpider
–
ChemSpider is a database of chemicals. ChemSpider is owned by the Royal Society of Chemistry, the database contains information on more than 50 million molecules from over 500 data sources including, Each chemical is given a unique identifier, which forms part of a corresponding URL. This is an approach to develop an online chemistry database. The search can be used to widen or restrict already found results, structure searching on mobile devices can be done using free apps for iOS and for the Android. The ChemSpider database has been used in combination with text mining as the basis of document markup. The result is a system between chemistry documents and information look-up via ChemSpider into over 150 data sources. ChemSpider was acquired by the Royal Society of Chemistry in May,2009, prior to the acquisition by RSC, ChemSpider was controlled by a private corporation, ChemZoo Inc. The system was first launched in March 2007 in a release form. ChemSpider has expanded the generic support of a database to include support of the Wikipedia chemical structure collection via their WiChempedia implementation. A number of services are available online. SyntheticPages is an interactive database of synthetic chemistry procedures operated by the Royal Society of Chemistry. Users submit synthetic procedures which they have conducted themselves for publication on the site and these procedures may be original works, but they are more often based on literature reactions. Citations to the published procedure are made where appropriate. They are checked by an editor before posting. The pages do not undergo formal peer-review like a journal article. The comments are moderated by scientific editors. The intention is to collect practical experience of how to conduct useful chemical synthesis in the lab, while experimental methods published in an ordinary academic journal are listed formally and concisely, the procedures in ChemSpider SyntheticPages are given with more practical detail. Comments by submitters are included as well, other publications with comparable amounts of detail include Organic Syntheses and Inorganic Syntheses

2.
PubChem
–
PubChem is a database of chemical molecules and their activities against biological assays. The system is maintained by the National Center for Biotechnology Information, a component of the National Library of Medicine, PubChem can be accessed for free through a web user interface. Millions of compound structures and descriptive datasets can be downloaded via FTP. PubChem contains substance descriptions and small molecules with fewer than 1000 atoms and 1000 bonds, more than 80 database vendors contribute to the growing PubChem database. PubChem consists of three dynamically growing primary databases, as of 28 January 2016, Compounds,82.6 million entries, contains pure and characterized chemical compounds. Substances,198 million entries, contains also mixtures, extracts, complexes, bioAssay, bioactivity results from 1.1 million high-throughput screening programs with several million values. PubChem contains its own online molecule editor with SMILES/SMARTS and InChI support that allows the import and export of all common chemical file formats to search for structures and fragments. In the text search form the database fields can be searched by adding the name in square brackets to the search term. A numeric range is represented by two separated by a colon. The search terms and field names are case-insensitive, parentheses and the logical operators AND, OR, and NOT can be used. AND is assumed if no operator is used, example,0,5000,50,10 -5,5 PubChem was released in 2004. The American Chemical Society has raised concerns about the publicly supported PubChem database and they have a strong interest in the issue since the Chemical Abstracts Service generates a large percentage of the societys revenue. To advocate their position against the PubChem database, ACS has actively lobbied the US Congress, soon after PubChems creation, the American Chemical Society lobbied U. S. Congress to restrict the operation of PubChem, which they asserted competes with their Chemical Abstracts Service

3.
International Chemical Identifier
–
Initially developed by IUPAC and NIST from 2000 to 2005, the format and algorithms are non-proprietary. The continuing development of the standard has supported since 2010 by the not-for-profit InChI Trust. The current version is 1.04 and was released in September 2011, prior to 1.04, the software was freely available under the open source LGPL license, but it now uses a custom license called IUPAC-InChI Trust License. Not all layers have to be provided, for instance, the layer can be omitted if that type of information is not relevant to the particular application. InChIs can thus be seen as akin to a general and extremely formalized version of IUPAC names and they can express more information than the simpler SMILES notation and differ in that every structure has a unique InChI string, which is important in database applications. Information about the 3-dimensional coordinates of atoms is not represented in InChI, the InChI algorithm converts input structural information into a unique InChI identifier in a three-step process, normalization, canonicalization, and serialization. The InChIKey, sometimes referred to as a hashed InChI, is a fixed length condensed digital representation of the InChI that is not human-understandable. The InChIKey specification was released in September 2007 in order to facilitate web searches for chemical compounds and it should be noted that, unlike the InChI, the InChIKey is not unique, though collisions can be calculated to be very rare, they happen. In January 2009 the final 1.02 version of the InChI software was released and this provided a means to generate so called standard InChI, which does not allow for user selectable options in dealing with the stereochemistry and tautomeric layers of the InChI string. The standard InChIKey is then the hashed version of the standard InChI string, the standard InChI will simplify comparison of InChI strings and keys generated by different groups, and subsequently accessed via diverse sources such as databases and web resources. Every InChI starts with the string InChI= followed by the version number and this is followed by the letter S for standard InChIs. The remaining information is structured as a sequence of layers and sub-layers, the layers and sub-layers are separated by the delimiter / and start with a characteristic prefix letter. The six layers with important sublayers are, Main layer Chemical formula and this is the only sublayer that must occur in every InChI. The atoms in the formula are numbered in sequence, this sublayer describes which atoms are connected by bonds to which other ones. Describes how many hydrogen atoms are connected to each of the other atoms, the condensed,27 character standard InChIKey is a hashed version of the full standard InChI, designed to allow for easy web searches of chemical compounds. Most chemical structures on the Web up to 2007 have been represented as GIF files, the full InChI turned out to be too lengthy for easy searching, and therefore the InChIKey was developed. With all databases currently having below 50 million structures, such duplication appears unlikely at present, a recent study more extensively studies the collision rate finding that the experimental collision rate is in agreement with the theoretical expectations. Example, Morphine has the structure shown on the right, as the InChI cannot be reconstructed from the InChIKey, an InChIKey always needs to be linked to the original InChI to get back to the original structure

4.
Simplified molecular-input line-entry system
–
The simplified molecular-input line-entry system is a specification in form of a line notation for describing the structure of chemical species using short ASCII strings. SMILES strings can be imported by most molecule editors for conversion back into two-dimensional drawings or three-dimensional models of the molecules, the original SMILES specification was initiated in the 1980s. It has since modified and extended. In 2007, a standard called OpenSMILES was developed in the open-source chemistry community. Other linear notations include the Wiswesser Line Notation, ROSDAL and SLN, the original SMILES specification was initiated by David Weininger at the USEPA Mid-Continent Ecology Division Laboratory in Duluth in the 1980s. The Environmental Protection Agency funded the project to develop SMILES. It has since modified and extended by others, most notably by Daylight Chemical Information Systems. In 2007, a standard called OpenSMILES was developed by the Blue Obelisk open-source chemistry community. Other linear notations include the Wiswesser Line Notation, ROSDAL and SLN, in July 2006, the IUPAC introduced the InChI as a standard for formula representation. SMILES is generally considered to have the advantage of being slightly more human-readable than InChI, the term SMILES refers to a line notation for encoding molecular structures and specific instances should strictly be called SMILES strings. However, the term SMILES is also used to refer to both a single SMILES string and a number of SMILES strings, the exact meaning is usually apparent from the context. The terms canonical and isomeric can lead to confusion when applied to SMILES. The terms describe different attributes of SMILES strings and are not mutually exclusive, typically, a number of equally valid SMILES strings can be written for a molecule. For example, CCO, OCC and CC all specify the structure of ethanol, algorithms have been developed to generate the same SMILES string for a given molecule, of the many possible strings, these algorithms choose only one of them. This SMILES is unique for each structure, although dependent on the algorithm used to generate it. These algorithms first convert the SMILES to a representation of the molecular structure. A common application of canonical SMILES is indexing and ensuring uniqueness of molecules in a database, there is currently no systematic comparison across commercial software to test if such flaws exist in those packages. SMILES notation allows the specification of configuration at tetrahedral centers, and these are structural features that cannot be specified by connectivity alone and SMILES which encode this information are termed isomeric SMILES

5.
Chemical formula
–
These are limited to a single typographic line of symbols, which may include subscripts and superscripts. A chemical formula is not a name, and it contains no words. Although a chemical formula may imply certain simple chemical structures, it is not the same as a full chemical structural formula. Chemical formulas can fully specify the structure of only the simplest of molecules and chemical substances, the simplest types of chemical formulas are called empirical formulas, which use letters and numbers indicating the numerical proportions of atoms of each type. Molecular formulas indicate the numbers of each type of atom in a molecule. For example, the formula for glucose is CH2O, while its molecular formula is C6H12O6. This is possible if the relevant bonding is easy to show in one dimension, an example is the condensed molecular/chemical formula for ethanol, which is CH3-CH2-OH or CH3CH2OH. For reasons of structural complexity, there is no condensed chemical formula that specifies glucose, chemical formulas may be used in chemical equations to describe chemical reactions and other chemical transformations, such as the dissolving of ionic compounds into solution. A chemical formula identifies each constituent element by its chemical symbol, in empirical formulas, these proportions begin with a key element and then assign numbers of atoms of the other elements in the compound, as ratios to the key element. For molecular compounds, these numbers can all be expressed as whole numbers. For example, the formula of ethanol may be written C2H6O because the molecules of ethanol all contain two carbon atoms, six hydrogen atoms, and one oxygen atom. Some types of compounds, however, cannot be written with entirely whole-number empirical formulas. An example is boron carbide, whose formula of CBn is a variable non-whole number ratio with n ranging from over 4 to more than 6.5. When the chemical compound of the consists of simple molecules. These types of formulas are known as molecular formulas and condensed formulas. A molecular formula enumerates the number of atoms to reflect those in the molecule, so that the formula for glucose is C6H12O6 rather than the glucose empirical formula. However, except for very simple substances, molecular chemical formulas lack needed structural information, for simple molecules, a condensed formula is a type of chemical formula that may fully imply a correct structural formula. For example, ethanol may be represented by the chemical formula CH3CH2OH

6.
Chemical compound
–
A chemical compound is an entity consisting of two or more atoms, at least two from different elements, which associate via chemical bonds. Many chemical compounds have a numerical identifier assigned by the Chemical Abstracts Service. For example, water is composed of two atoms bonded to one oxygen atom, the chemical formula is H2O. A compound can be converted to a different chemical composition by interaction with a chemical compound via a chemical reaction. In this process, bonds between atoms are broken in both of the compounds, and then bonds are reformed so that new associations are made between atoms. Schematically, this reaction could be described as AB + CD → AC + BD, where A, B, C, and D are each unique atoms, and AB, CD, AC, and BD are each unique compounds. A chemical element bonded to a chemical element is not a chemical compound since only one element. Examples are the diatomic hydrogen and the polyatomic molecule sulfur. Chemical compounds have a unique and defined chemical structure held together in a spatial arrangement by chemical bonds. Pure chemical elements are not considered chemical compounds, failing the two or more atom requirement, though they often consist of molecules composed of multiple atoms. There is varying and sometimes inconsistent nomenclature differentiating substances, which include truly non-stoichiometric examples, from chemical compounds, other compounds regarded as chemically identical may have varying amounts of heavy or light isotopes of the constituent elements, which changes the ratio of elements by mass slightly. Characteristic properties of compounds include that elements in a compound are present in a definite proportion, for example, the molecule of the compound water is composed of hydrogen and oxygen in a ratio of 2,1. In addition, compounds have a set of properties. The physical and chemical properties of compounds differ from those of their constituent elements, however, mixtures can be created by mechanical means alone, but a compound can be created only by a chemical reaction. Some mixtures are so combined that they have some properties similar to compounds. Other examples of compound-like mixtures include intermetallic compounds and solutions of metals in a liquid form of ammonia. Compounds may be described using formulas in various formats, for compounds that exist as molecules, the formula for the molecular unit is shown. For polymeric materials, such as minerals and many metal oxides, the elements in a chemical formula are normally listed in a specific order, called the Hill system

7.
Structural isomer
–
Structural isomerism, or constitutional isomerism, is a form of isomerism in which molecules with the same molecular formula have bonded together in different orders, as opposed to stereoisomerism. There are multiple synonyms for constitutional isomers, three categories of constitutional isomers are skeletal, positional, and functional isomers. Positional isomers are also called regioisomers, in chain isomerism, or skeletal isomerism, components of the skeleton are distinctly re-ordered to create different structures. Pentane exists as three isomers, n-pentane, isopentane and neopentane, in position isomerism a functional group or other substituent changes position on a parent structure. In the table below, the group can occupy three different positions on an n-pentane chain forming three different compounds. Many aromatic isomers exist because substituents can be positioned on different parts of the benzene ring, only one isomer of phenol or hydroxybenzene exists but cresol or methylphenol has three isomers where the additional methyl group can be placed on three different positions on the ring. Xylenol has one group and two methyl groups and a total of 6 isomers exist. Functional isomers are structural isomers that have the molecular formula. These groups of atoms are called groups, functionalities. Another way to say this is that two compounds with the molecular formula, but different functional groups, are functional isomers. For example, cyclohexane and 1-hexene both have the formula C6H12 and these two are considered functional group isomers because cyclohexane is a cycloalkane and hex-1-ene is an alkene. For two molecules to be functional isomers, they must contain key groups of atoms arranged in particular ways, some of the best examples come from organic chemistry. Depending on how the atoms are arranged, it can represent two different compounds dimethyl ether CH3-O-CH3 or ethanol CH3CH2-O-H, dimethyl ether and ethanol are functional isomers. The carbon chain-oxygen-carbon chain functionality is called an ether, the carbon chain-oxygen-hydrogen functionality is called an alcohol. If the functionalities stay the same, but their locations change, 1-Propanol and 2-propanol are structural isomers, but they are not functional isomers. The functional group is present in both of these compounds, but they are not the same, while some chemists use the terms structural isomer and functional isomer interchangeably, not all structural isomers are functional isomers. Functional isomers are most often identified in chemistry using infrared spectroscopy, infrared radiation corresponds to the energies associated primarily with molecular vibration. The alcohol functionality has a very distinct vibration called OH-stretch that is due to hydrogen bonding, all alcohols in liquid and solid form absorb infrared radiation at certain wavelengths

8.
Refrigerant
–
A refrigerant is a substance or mixture, usually a fluid, used in a heat pump and refrigeration cycle. In most cycles it undergoes phase transitions from a liquid to a gas, many working fluids have been used for such purposes. Fluorocarbons, especially chlorofluorocarbons, became commonplace in the 20th century, other common refrigerants used in various applications are ammonia, sulfur dioxide, and non-halogenated hydrocarbons such as propane. The ideal refrigerant would have favorable properties, be noncorrosive to mechanical components. It would not cause ozone depletion or climate change, since different fluids have the desired traits in different degree, choice is a matter of trade-off. Since boiling point and gas density are affected by pressure, refrigerants may be more suitable for a particular application by choice of operating pressures. In order from the highest to the lowest potential of ozone depletion are Bromochlorofluorocarbon, though HFC and PFC are non-ozone depleting, many have global warming potentials that are thousands of times greater than CO2. Some other refrigerants such as propane and ammonia are not inert, new refrigerants were developed in the early 21st century that are safer for the environment, but their application has been held up due to concerns over toxicity and flammability. Early mechanical refrigeration systems employed sulfur dioxide, methyl chloride and ammonia, being toxic, sulfur dioxide and methyl chloride rapidly disappeared from the market with the introduction of CFCs. Occasionally, one may encounter older machines with methyl formate, chloromethane, chlorofluorocarbons were little used for refrigeration until better synthesis methods, developed in the 1950s, reduced their cost. Their domination of the market was called into question in the 1980s by concerns about depletion of the ozone layer and they are currently subject to prohibition discussions on account of their harmful effect on the climate. In 1997, FCs and HFCs were included in the Kyoto Protocol to the Framework Convention on Climate Change, in 2006, the EU adopted a Regulation on fluorinated greenhouse gases, which makes stipulations regarding the use of FCs and HFCs with the intention of reducing their emissions. The provisions do not affect climate-neutral refrigerants, refrigerants such as ammonia, carbon dioxide and non-halogenated hydrocarbons do not deplete the ozone layer and have no or only a low global warming potential. They are used in air-conditioning systems for buildings, in sport and leisure facilities, in the industry, in the automotive industry. In these settings their toxicity is less a concern than in home equipment, emissions from automobile air conditioning are a growing concern because of their impact on climate change. From 2011 on, the European Union will phase out refrigerants with a global warming potential of more than 150 in automotive air conditioning and this will ban potent greenhouse gases such as the refrigerant HFC-134a —which has a GWP of 1410—to promote safe and energy-efficient refrigerants. One of the most promising alternatives is CO2, carbon dioxide is non-flammable, non-ozone depleting, has a global warming potential of 1. R-744 can be used as a fluid in climate control systems for cars, residential air conditioning, hot water pumps, commercial refrigeration

9.
Hazardous chemical
–
Dangerous goods or hazardous goods are solids, liquids, or gases that can harm people, other living organisms, property, or the environment. They are often subject to chemical regulations, in the United States, United Kingdom and sometimes in Canada, dangerous goods are more commonly known as hazardous materials. In the United States, dangerous goods are often indicated by diamond-shaped signage on the item, its container, mitigating the risks associated with hazardous materials may require the application of safety precautions during their transport, use, storage and disposal. Most countries regulate hazardous materials by law, and they are subject to international treaties as well. Even so, different countries may use different class diamonds for the same product, for example, in Australia, Anhydrous Ammonia UN1005 is classified as 2.3 with sub risk 8, whereas in the U. S. it is only classified as 2.2. People who handle dangerous goods will often wear protective equipment, and metropolitan fire departments often have a team specifically trained to deal with accidents. Laws and regulations on the use and handling of materials may differ depending on the activity. For example, one set of requirements may apply to their use in the workplace while a different set of requirements may apply to spill response, sale for consumer use, most countries regulate some aspect of hazardous materials. The most widely applied regulatory scheme is that for the transportation of dangerous goods, individual airline and governmental requirements are incorporated with this by the International Air Transport Association to produce the widely used IATA Dangerous Goods Regulations. Similarly, the International Maritime Organization has developed the International Maritime Dangerous Goods Code for transportation of goods by sea. IMO member countries have developed the HNS Convention to provide compensation in case of dangerous goods spills in the sea. The Intergovernmental Organisation for International Carriage by Rail has developed the Regulations concerning the International Carriage of Dangerous Goods by Rail, many individual nations have also structured their dangerous goods transportation regulations to harmonize with the UN Model in organization as well as in specific requirements. GHS will use consistent criteria for classification and labeling on a global level, Dangerous goods are divided into nine classes on the basis of the specific chemical characteristics producing the risk. Note, The graphics and text in this article representing the dangerous goods safety marks are derived from the United Nations-based system of identifying dangerous goods, not all countries use precisely the same graphics in their national regulations. Some use graphic symbols, but without English wording or with similar wording in their national language, refer to the Dangerous Goods Transportation Regulations of the country of interest. For example, see the TDG Bulletin, Dangerous Goods Safety Marks based on the Canadian Transportation of Dangerous Goods Regulations, the statement above applies equally to all the Dangerous Goods classes discussed in this article. Australia uses the standard international UN numbers with a few slightly different signs on the back, front, the country uses the same Hazchem code system as the UK to provide advisory information to emergency services personnel in the event of an emergency. New Zealands Land Transport Rule, Dangerous Goods 2005 and the Dangerous Goods Amendment 2010 describe the rules applied to the transportation of hazardous and dangerous goods in New Zealand

10.
MSDS
–
A safety data sheet, material safety data sheet, or product safety data sheet is an important component of product stewardship, occupational safety and health, and spill-handling procedures. SDS formats can vary from source to source within a country depending on national requirements, SDSs are a widely used system for cataloging information on chemicals, chemical compounds, and chemical mixtures. SDS information may include instructions for the use and potential hazards associated with a particular material or product. The SDS should be available for reference in the area where the chemicals are being stored or in use, there is also a duty to properly label substances on the basis of physico-chemical, health and/or environmental risk. Labels can include hazard symbols such as the European Union standard symbols, a SDS for a substance is not primarily intended for use by the general consumer, focusing instead on the hazards of working with the material in an occupational setting. It is important to use an SDS specific to country and supplier, as the same product can have different formulations in different countries. The formulation and hazard of a product using a name may vary between manufacturers in the same country. Safety data sheets have made an integral part of the system of Regulation No 1907/2006. The SDS must be supplied in a language of the Member State where the substance or mixture is placed on the market. The 16 sections are, SECTION1, Identification of the substance/mixture, relevant identified uses of the substance or mixture and uses advised against 1.3. Details of the supplier of the safety data sheet 1.4, Emergency telephone number SECTION2, Hazards identification 2.1. Classification of the substance or mixture 2.2, Other hazards SECTION3, Composition/information on ingredients 3.1. Mixtures SECTION4, First aid measures 4.1, Description of first aid measures 4.2. Most important symptoms and effects, both acute and delayed 4.3, indication of any immediate medical attention and special treatment needed SECTION5, Firefighting measures 5.1. Special hazards arising from the substance or mixture 5.3, advice for firefighters SECTION6, Accidental release measure 6.1. Personal precautions, protective equipment and emergency procedures 6.2, methods and material for containment and cleaning up 6.4. Reference to other sections SECTION7, Handling and storage 7.1, conditions for safe storage, including any incompatibilities 7.3. Specific end use SECTION8, Exposure controls/personal protection 8.1, Exposure controls SECTION9, Physical and chemical properties 9.1

11.
ASHRAE
–
ASHRAE, stands for the American Society of Heating, Refrigerating and Air-Conditioning Engineers. If was founded in 1894 and has more than 50,000 members worldwide and it focuses on building systems, energy efficiency, indoor air quality, refrigeration and sustainability technologies. The ASHRAE was founded in 1894 at a meeting of engineers in New York City, formerly headquartered at 345 East 47th Street, and has held an annual meeting since 1895. Until 1954 it was known as the American Society of Heating and Ventilating Engineers and its current name and organization came from the 1959 merger of ASHAE and the American Society of Refrigerating Engineers. Despite having American in its name, ASHRAE is a global organization, in 2012, it rebranded itself with a new logo and tagline, Shaping Tomorrows Built Environment Today. The volumes are Fundamentals, HVAC Applications, HVAC Systems and Equipment, one of the four volumes is updated each year. These standards are reviewed, revised and republished. ASHRAE Journal is issued monthly and High Performing Buildings Magazine quaterly and they contain articles on related technology, information on upcoming meetings, editorials, and case studies of various well-performing buildings. ASHRAE also publishes books, ASHRAE Transactions, and the International Journal of HVAC&R Research, to demonstrate the Society’s commitment to sustainability, ASHRAE renovated its existing headquarters building in Atlanta, Ga. After the renovation and occupancy in June 2008, the building has received awards, including an Energy Star rating with a score of 95. The current site energy use intensity is 35.8 kBtu/Sqft, the building also serves as a live case study

12.
Journal of the American Chemical Society
–
The Journal of the American Chemical Society is a weekly peer-reviewed scientific journal that was established in 1879 by the American Chemical Society. The journal has absorbed two other publications in its history, the Journal of Analytical and Applied Chemistry and the American Chemical Journal and it publishes original research papers in all fields of chemistry. Since 2002, the journal is edited by Peter J. Stang, in 2014, the journal moved to a hybrid open access publishing model. The Journal of the American Chemical Society is abstracted and indexed in Chemical Abstracts Service, Scopus, EBSCOhost, Thomson-Gale, ProQuest, PubMed, Web of Science, and SwetsWise. According to the Journal Citation Reports, it had a factor of 12.113 for 2014

ChemSpider
–
ChemSpider is a database of chemicals. ChemSpider is owned by the Royal Society of Chemistry, the database contains information on more than 50 million molecules from over 500 data sources including, Each chemical is given a unique identifier, which forms part of a corresponding URL. This is an approach to develop an online chemistry database. The

1.
ChemSpider

PubChem
–
PubChem is a database of chemical molecules and their activities against biological assays. The system is maintained by the National Center for Biotechnology Information, a component of the National Library of Medicine, PubChem can be accessed for free through a web user interface. Millions of compound structures and descriptive datasets can be dow

1.
PubChem

International Chemical Identifier
–
Initially developed by IUPAC and NIST from 2000 to 2005, the format and algorithms are non-proprietary. The continuing development of the standard has supported since 2010 by the not-for-profit InChI Trust. The current version is 1.04 and was released in September 2011, prior to 1.04, the software was freely available under the open source LGPL lic

1.
L - ascorbic acid

Simplified molecular-input line-entry system
–
The simplified molecular-input line-entry system is a specification in form of a line notation for describing the structure of chemical species using short ASCII strings. SMILES strings can be imported by most molecule editors for conversion back into two-dimensional drawings or three-dimensional models of the molecules, the original SMILES specifi

1.
Generation of SMILES: Break cycles, then write as branches off a main backbone. (Ciprofloxacin)

Chemical formula
–
These are limited to a single typographic line of symbols, which may include subscripts and superscripts. A chemical formula is not a name, and it contains no words. Although a chemical formula may imply certain simple chemical structures, it is not the same as a full chemical structural formula. Chemical formulas can fully specify the structure of

1.
Al 2 (SO 4) 3

Chemical compound
–
A chemical compound is an entity consisting of two or more atoms, at least two from different elements, which associate via chemical bonds. Many chemical compounds have a numerical identifier assigned by the Chemical Abstracts Service. For example, water is composed of two atoms bonded to one oxygen atom, the chemical formula is H2O. A compound can

1.
Pure water (H 2 O) is an example of a compound: the ball-and-stick model of the molecule (above) shows the spatial association of two parts hydrogen (white) and one part oxygen (red)

Structural isomer
–
Structural isomerism, or constitutional isomerism, is a form of isomerism in which molecules with the same molecular formula have bonded together in different orders, as opposed to stereoisomerism. There are multiple synonyms for constitutional isomers, three categories of constitutional isomers are skeletal, positional, and functional isomers. Pos

Refrigerant
–
A refrigerant is a substance or mixture, usually a fluid, used in a heat pump and refrigeration cycle. In most cycles it undergoes phase transitions from a liquid to a gas, many working fluids have been used for such purposes. Fluorocarbons, especially chlorofluorocarbons, became commonplace in the 20th century, other common refrigerants used in va

Hazardous chemical
–
Dangerous goods or hazardous goods are solids, liquids, or gases that can harm people, other living organisms, property, or the environment. They are often subject to chemical regulations, in the United States, United Kingdom and sometimes in Canada, dangerous goods are more commonly known as hazardous materials. In the United States, dangerous goo

MSDS
–
A safety data sheet, material safety data sheet, or product safety data sheet is an important component of product stewardship, occupational safety and health, and spill-handling procedures. SDS formats can vary from source to source within a country depending on national requirements, SDSs are a widely used system for cataloging information on che

1.
An example SDS in a US format provides guidance for handling a hazardous substance and information on its composition and properties.

2.
General topics

ASHRAE
–
ASHRAE, stands for the American Society of Heating, Refrigerating and Air-Conditioning Engineers. If was founded in 1894 and has more than 50,000 members worldwide and it focuses on building systems, energy efficiency, indoor air quality, refrigeration and sustainability technologies. The ASHRAE was founded in 1894 at a meeting of engineers in New

1.
ASHRAE logo

Journal of the American Chemical Society
–
The Journal of the American Chemical Society is a weekly peer-reviewed scientific journal that was established in 1879 by the American Chemical Society. The journal has absorbed two other publications in its history, the Journal of Analytical and Applied Chemistry and the American Chemical Journal and it publishes original research papers in all fi